What is ISO and how to configure it

ISO value is one of the most important parameters when shooting, along with such values ​​as excerpts, aperture and white balance. ISO is often referred to as ISO sensitivity, ISO level, or simply photosensitivity matrix or film.

Poster for the article. What is ISO?

Poster for the article. What is ISO?

Still, what is ISO in the settings of the camera?

ISO Is a parameter indicating the level sensitivity to light of its light-picking element (matrices or films). Basically indicate the limits of ISO for cameras (cameras). Although, the same parameter can be found not only on the camera, but, for example, on the flash. For flash, a guide number is usually indicated when using one of the ISO values ​​of 100, or 200. ISO sensitivity indicated in special units of the ISO system. The ISO numeric expression itself can accept any integer expression from 1 to infinity. For example, on my flash SB-900 you can set the ISO from 1 (unit) to 12,500, and on my camera Nikon D40 You can set the ISO value from 200 to 1.600.

Less is better!

The higher the ISO value, the more photosensitive the matrix. It is very important to understand that the higher the ISO value, the less time it takes for the matrix or film to scan the image from the lens. For clarity, I’ll give an example: we shoot in the evening, there is little light, the camera is set to ISO 100, while the camera in the aperture priority (or in any other mode) shows that the picture will be taken with shutter speed 1 / 20s. It is very long excerpt, and at the same time we can get a blurry frame. Because, to reduce shutter speed need to increase ISO. For example, we increased the ISO to 800, while doing so excerpt decrease by 8 times and become 1 / 160s (one hundred and sixtieth seconds). If it weren’t for noise, then one could always shoot at high ISO and never worry about exposure; due to noise, you need to lower ISO and increase exposure and in addition worry about not getting a blurry shot.

Raise, close, reduce!

Parameters excerpts, aperture values ​​and ISO are interchangeable. The amount of light needed for the camera to build the image can be the same for different three values excerpts, aperture and ISO. So, at values ​​of 1 / 60s, F2.8, ISO 100, the camera will receive as much light as at values ​​of 1 / 30s, F2.8, ISO 50 or 1 / 60s, F5.6, ISO 400. In order to compensate raising ISO, you need to close the aperture or reduce shutter speed. The opposite is also true. You can increase shutter speed, open aperture and lower ISO.

ISO affects noise

In fact, the ISO value is also responsible for the appearance of noise in the photo.. Noise is a parasitic distortion in a photograph. Usually they call it that - noise, grain, etc. The higher the ISO, the greater the noise.. And the lower the ISO, the less noise will be. To get the best possible high-quality photo from the camera, you need to shoot at the highest permissible low ISO. Very often it is ISO 200, 100, 50, sometimes they can be designated as Lo1.

Noise difference at different ISO values

Noise difference at different ISO values

Super high and super low ISO

Many cameras have extended ISO range - usually this is software wrapping ISO, and they are designated as Hi1, Hi2, etc. For example, for a camera Nikon D200 HI1 is equivalent to ISO 3200 and on camera Nikon D90 HI1 is equivalent to the value of ISO 6400. Always remember that when shooting at such advanced ISO values ​​there will almost always be a very strong picture noise effect. I strongly recommend not shooting in the extended upper ISO range on any cameras. Also, the range can expand in a smaller direction, so the camera Nikon D90, D300, D700 matter 1, 0.3, 0.7 as equivalents for ISO 100, 160, 130. What is the benefit of expanding to a low ISO range, see my ISO article lo1. Some cameras, in fact, do not have a hardware implementation of ISO, I made this conclusion after ISO experiment.

Noise at different ISO. Example 1 to 1 increase

Noise at different ISO. Example 1 to 1 increase

With which ISO to choose a camera?

When choosing a camera, always look at the minimum and maximum ISO values, and also remember that in 90% of cases you do not have to shoot at extremely high ISOs, since often they simply can not ensure normal image quality. Therefore, professional photographers have ISO working concept. By working ISO is meant the maximum ISO value at which the camera can give an acceptable result. The trick is that unlike the diaphragm and excerpts, which on all cameras give completely the same values, the same ISO on different cameras can give different noise values. Therefore, in one camera, the working ISO will be 800, and in the other, the working ISO will be 3200. For example, on the camera Nikon D700 images of acceptable quality can be obtained at ISO 3200, while at Nikon D200 in ISO 3200 (Hi1) mode, it’s already not a photograph, but complete nonsense. The difference in ISO noise is very strongly felt on digital soap dishes, where digital noise is often very visible already on ISO 400, but at the same time, ISO 400 is quite operational on SLR cameras.

What affects noise at high ISO?

The noise level at high ISO is very much affected matrix size camera. The larger the matrix, the less noise. Given that the matrix is ​​very small in compact cameras, it produces a huge noise level. The explanation can be very simple at the pixel size. The large matrix has large pixels that can absorb a lot more light and thus make a strong electrical signal. It is logical that 12MP with soap dishes and 12MP with Nikon D3s will produce different noise levels at high ISO. More information in my article. matrix size has the meaning.

How is ISO measured?

ISO as well as shutter speed and aperture accepted count in the footstepseg ISO 100, ISO 200, ISO 400, etc. The difference between ISO 800 and ISO 400 is exactly two times or one stop, and between ISO 100 and ISO 1600 exactly 16 times, or 4 stops. It's too bad that cameras generally only allow ISO changes by stop value. So, for Nikon D40 it is possible to manually set ISO only 200, 400, 800, 1600, HI1, and you cannot set an intermediate value such as ISO 250, 320, 500, etc. On more advanced cameras, you can set intermediate values, but still fine ISO control is practically not in any cell. The most interesting thing is that in the automatic ISO mode, the ISO sensitivity can take on any values, such as 110, 230, 1400, etc.

Auto ISO

On almost all cameras available auto ISO. This means that the camera itself will select the optimal ISO value. Auto ISO It is very convenient when shooting with poor lighting, when using it, the camera can squeeze the maximum quality. Basically, when using auto ISO, The maximum shutter speed and maximum ISO value must be indicated. Some cameras adjust the ISO to the focal length of the lens to prevent blur when shooting with your hands. Who cares, you can read how the function of automatic control of ISO sensitivity works on modern Nikon central control centers.

Auto ISO Example

We decided to photograph the cat at home in the dim light of the lamp. We have a 60mm lens, to avoid hand shake, you need to shoot at a shutter speed no longer than 1/60, so we set the maximum shutter speed to 1/60 in the automatic ISO settings, as well as the maximum allowable ISO 800 in order to get the maximum picture quality. When photographing, the camera will try to lower the ISO, and adjust the shutter speed. If the shutter speed is shorter than 1/60 and the ISO is less than the minimum, the camera will automatically extend the shutter speed and lower the ISO and will do so until it hits the preset limit of 1/60 second, while we get the maximum allowable shutter speed and the lowest possible ISO for photographing a cat. If there is enough light, the camera will set ISO 100 (or any minimum acceptable) and any desired shutter speed no longer than 1/60. If the light is catastrophically small, then the camera will set the maximum possible ISO and forcibly increase the shutter speed for the correct exposure. Generally, I I strongly recommend experimenting with auto ISO in aperture priority modesince the operation of automatic ISO is quite specific.

Little trick

When using automatic ISO and flash, it is better to turn off the auto ISO, since very often the camera goes crazy and where you can really lower the ISO, the camera sets the maximum specified and takes a picture with flash. Anyway, if there is a flash, then you can safely use the lowest available ISO.

Another little trick

On a number of DSLR cameras in the auto ISO mode, you can set the maximum ISO in the menu, as well as the minimum. Sometimes, to set the minimum ISO, you just need to set the desired ISO value with the selector, for example, 800. And then, with the maximum specified ISO 1600, you get a working range of ISO 800-1600 at which the camera will work - a very, very useful thing.

Golden ISO Rule

Always remember the golden rule - you need to shoot at the lowest possible ISO. As soon as there is an opportunity to lower the ISO - do it. Raise the ISO only when needed, such as when the shutter speed at low ISO is too slow for normal handheld shooting. To lower the ISO as low as possible - open the aperture as much as possible. If there is a flash, do not use high ISO. Although, sometimes with the flash, you can shoot at high ISO (details here).


Value ISO directly responsible for photosensitivity and noise level. The higher the ISO, the greater the noise and the worse the photo. Lower ISO - the better the photo, but the longer the shutter speed.

 Have a question? You can ask in the comments. Thanks for attention. Arkady Shapoval.

Add a comment:



Comments: 149, on the topic: What is ISO and how to configure it

  • Oleg

    Arkady, can you tell me if there is an opportunity to set the ISO interal, say, in the range 200 ... 1600 on the D90? And is it possible to install auto-ISO using hot-keys or only through the menu? If so, how do you do it? I photograph a child, and very often I need to grab the camera and catch the moment, my hands do not reach the ISO, so I keep it in AUTO, and the camera is often upset by the prohibitive ISO values.
    Thank you very much for your work, very much appreciated !!!

    • Arkady Shapoval

      Yes there is. In the auto iso menu, select the maximum, and using the ISO button on the camera, set the minimum, thus you get, for example, an interval of 800-2000. Regarding the setting for the function key - I don't remember if it can be customized.

  • Valery

    Everything is accessible and understandable. Thanks. Tell me please. I am new to Nikon D5100. In what format is it better to save photos? High quality JPEG or NEF (RAW) + high quality JIPEG. And what does that mean?

  • Eugene

    Arkady, please tell me why the photo turns out to be dark when I set a small shutter speed? ... and the slower the shutter speed, the darker the photo ...

    • Arkady Shapoval

      So it should be, exposure doses the light.

      • anonym

        Thanks for the reply.

  • inishka

    What is the maximum (upper) ISO limit to set for normal snapshots? On nikon 1 j1

  • Ildar

    Arkady, thanks for the article!
    But I can’t figure out when to increase the ISO, and when to add exposure to +? In the case of ISO - an increase only spoils the picture, but if you add exposure to + then no grain will appear and the picture will become brighter
    Thanks in advance for the comment.

    • Arkady Shapoval

      It is necessary to increase when the shutter speed at low ISO is too long.

  • Yana

    Arkady, hello, is it worth leaving the Nikon d90 iso with automatic shooting on Lo-1? or is it better to put on 500? Your opinion?))

  • Igor

    Arkady, tell me please, is it possible in AUTO mode to set boundaries for ISO, for example, from 50 to 200?

    • Arkady Shapoval

      Each camera is different, you need to look at the immediate instance of the camera.

  • Andrei

    Uv. readers of this blog! I am amazed at Arkady's patience in giving answers to questions that are chewed in the most detailed way in the article. You are writing, thank you Arkady, what a fine fellow you are. It really is. So respect human labor! Read the articles carefully! Written - best quality at lowest ISO! As long as the shutter speed is fast enough for these shooting tasks (subject mobility, focal length, etc.) If we do not fit with the shutter speed and the aperture cannot be increased, we gradually increase the ISO until we hit the noise level. Then we either change the lens to a faster one or look for a camera with less noise at higher ISOs. In my opinion, the ability of DSLRs to shoot normal photos at high ISO is one of their main advantages over soap cameras with small matrix sizes (there is also autofocus speed, DOF, etc.). Who offended - sorry. Nothing personal. Respect to Arkady.

    • Arkady Shapoval

      Thanks. You can still think about the flash.

      • Andrei

        Yes, of course, Arkady - or another lens or camera or additional light sources (flash)

  • Vladimir

    Uv.readers !!! I'm not even surprised that on the internet you can become any san-sei for any question ... they asked you and went to rummage in the internet to cleverly answer ... there is but !!! personally acquainted with Arkady and there was a case of 6-7 months in 2012, they handed a digital camera and asked to set it up… .so !!! Andrey's answer was that !!! I myself take pictures of the car and do not really understand… and just put everything on the car. So I'm not a professional ... but I will say one thing !!!! to know what and how to learn from professionals and the concept of light ... that is, how the human eye is the same and exposure and iso and aperture ... the lesson is over

    • anonym

      How to get blurry background in auto mode?

  • Vladimir

    sorry mixed it up with the wrong person ...

  • Igor

    One more subtlety. At a given ISO value, noise is less noticeable in bright colors. Therefore, images look cleaner, the plot important part of which is light. Pay attention to the composition. For example, remove from the frame lighter objects than the one you need - then, with the correct exposure, the fragment you need will turn out to be lighter and cleaner. It happens that, other things being equal, a frame at ISO 1600 does not look noisier than another frame at ISO 400. Accordingly, for one composition the working ISO can be 1600, and for another - 400.
    Moral: Don't skimp on ISO if you end up with an underexposed shot, and optimize your composition! This is especially important for cameras with a not very wide dynamic range at low ISO (from modern models - all compacts and cropped Canon, see the DxO data for reference).

  • Igor

    PS In the “compacts” I have included all cameras with a sensor size smaller than APS-C. And I also emphasize: an underexposed frame at ISO 100 will look noisier (especially after correcting tones) than a normally exposed frame at ISO 200!

  • Koss

    Greetings! Thanks for the articles (ISO, aperture, shutter speed).
    Fotik bought, most recently (about 2 weeks), took a budget SONY A450,
    After reading the articles and comments, I understood only one thing, that all the meanings (ISO, excerpt, dia.) Depend mainly only on a specific situation, you can forget about any “golden” mean, all by typing)))
    PS - AUTO ISO - on SONY is present.

  • Alexander

    I have a Canon 1100, with an increase of ISO to 400, the quality is already lost, let alone 3200! raise in the afternoon, if you need to remove for example a bird in flight. Noise is not visible during the day. Yes, and in general at high ISOs, the pixels light up against a dark background. Therefore, stationary objects have to be removed before exposure 1/4. I shot it with the same camera without stabilizing the lens, it smears already at 1/10.
    By the way, I had a Canon powershot sx 130 ultrasound so it’s generally easier to shoot at dusk than 1100. At aperture 3,5, the normal depth of field is, and you have to close the SLR to at least 5,6 if you are shooting a city landscape. Strange, but in the 130 soap dish, the image stabilizer works very well despite the price. It’s better to forget about ISO except 80.

  • Alexander

    Good afternoon.
    I don’t quite understand one moment. Many sites have the work of good photographers, with rather strange meanings. For example:
    NIKON D7000; Nikon AF-S Nikkor 35mm F / 1.8G; 1/1250 sec; F / 1.8; ISO400.
    Why is the standard landscape shot at ISO400 if there is enough shutter speed to compensate for everything?
    Thanks for the reply.

    • Arkady Shapoval

      This is a personal right of every photographer. On modern cameras, the difference in noise ISO 400, ISO 100 can not be felt. Also, the widest DD camera does not always fall at the lowest ISO values.

  • Sergei

    Good afternoon!
    I found a Zenit-E camera in the “basement”. First, I want to learn from this unit in order to acquire something more serious. I would like to clarify about the exposure: here, I think, is the standard exposure of the film, for example. 400. As I understand it, there is no talk of lowering ISO here. Here you need to work with aperture and shutter speed. Sunny day - close-decrease, darker - open-increase?

  • Andrei

    Thank you for the article! Tell me, Arkady - for Nikon d3100, what range of auto ISO to deliver?

    • Stas

      depending on where shooting is meant, street 100-200, apartment 200-400, night evening forest yard, etc. 400-600-800 and there should be happiness, but do not forget about endurance somewhere 1000 will be somewhere 125-60-30, read on on this site everything is about everything. Good luck.

      • Andrei

        Thank you, Stas!

      • Alien

        I think that in auto mode it is better not to limit the lower border - to leave the minimum possible (hardware) for each model.

  • Stas

    Yes, who has not worked with film cameras is hard to understand this, on the film there is simply nothing to add if it is written on the box 60 - 100 - 120 - 250 iso then you will not jump over and thought before that you would take a film for the street 60-100 for registry office 120-250 cafe 250-350 and it always turned out gorgeous, but wait half the camera thinks itself and she needs help to limit, then chic. and sometimes you read reviews about a good device and write that it sucks, like the pictures are very bad, then it's funny to become ... you just need to turn on your head and more practice. The article is very good, God forbid, who needs to understand.

  • Pasha

    Arkady, thanks for your articles and answers. You have iron nerves :)

  • Valya

    For me ISO is DV. 6 DV - one stage.

  • Nataly

    I have a Canon IXUS 990 IS soap box ... there is ISO 3200 in the settings .... somehow accidentally put on this mode, the pictures turned out to be disgusting, and did not understand why it was needed at all ??? Thanks.

  • Anastasia

    I bought a Canon 600D recently. The photos are grainy. And if you reduce the ISO, then the shutter speed is very long. Tell me, what can I do?

    • AX

      Use the flash, increase aperture, use a tripod. Depends on what you shoot.

  • ellen

    Please tell the newcomer, I have nikon d3100 which iso would always be optimal, so to speak working

  • Rahman

    Hello Arkady! I have a Nikon d7100 and I just can’t understand how to control Iso indoors and outdoors, tell me if it's not difficult! Thank you in advance))

  • Maksim

    Good afternoon, Arkady. I heard that it is undesirable to shoot at a minimum ISO value (there is no extreme minimum type LO1 in mind) as this reduces the DD and the color richness. For example, if the minimum ISO is 100, then it is advised to shoot at least 200. What do you think about this? Thanks.

Add a comment

Copyright © Radojuva.com. Blog author - Photographer in Kiev Arkady Shapoval. 2009-2022

English-version of this article https://radojuva.com/en/2012/01/what-is-iso/comment-page-2/

Versión en español de este artículo https://radojuva.com/es/2012/01/what-is-iso/comment-page-2/